This is an arithmetic sequence because each term is 7 greater than the previous term, so 7 is what is called the common difference...
Any arithmetic sequence can be expressed as:
a(n)=a+d(n-1), a=first term, d=common difference, n=term number.
We know a=1 and d=7 so:
a(n)=1+7(n-1)
a(n)=1+7n-7
a(n)=7n-6
The above is the "rule" for the nth term.
20 x 2=40
10 x 4=40
8 x 5= 40
so 2 bags of balloons
4 bags of horns
5 packages of candy

Collecting like terms,

Since the signs change when its position changes.

B. 42 degrees
Angle ABC is an inscribed angle so u have to divide Arc AC by 2 to find angle ABC.
84degrees divided by 2 is 42 degrees.
You would add them together if it’s on a number line bc u have to go 5 to get to 0 then another 13 so 13+5=18